If you were swinging from a bar, and you worked up enough speed to be spinning around the bar in a circular motion, then let go... how would the momentum follow through? When you let go, would you continue to arc in the general direction you were facing when you let go, or would you go straight in that direction?
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If there were no outside forces acting on you you'd go straight with the same velocity (same speed and direction) forever.
However, gravity exists, so you'd go straight and eventually arc due to gravity.
However, gravity exists, so you'd go straight and eventually arc due to gravity.